Number of coral bleaching events, World

The number of moderate (up to 30% of corals affected) and severe coral bleaching events (more than 30% of corals) measured at 100 fixed global locations. Bleachingoccurs when stressful conditions cause corals to expel their algal symbionts.

1980198219841986198819901992199419961998200020022004200620082010201220142016Moderate (<30%)Severe (>30%)